As of late, various methodologies and devices have been developed or are currently under development for the detection of explosives, and other contraband of various quantities, and which might be utilized in terrorist acts. Currently, vehicles and containers entering restricted areas such as military bases, courtrooms and facilities for public transportation are checked for contraband by means of physical search, x-ray, vapor detection or canine units who are deployed by law enforcement or other military personnel. Heretofore, various automatic spectral analysis routines have been developed and which are useful in the detection of explosives which might be concealed on vehicles, containers and the like. Such systems have included methodology and apparatus for interrogating a vehicle or container with neutrons provided by a neutron generator and thereafter collecting the gamma energy generated by the presence of any explosive substance by utilizing sodium iodide detectors. In these earlier devices and methodology, the typical gamma-ray spectrum collected was then analyzed based upon Gaussian peak fitting including peak deconvolution in order to identify the explosive substance. While the methodology and devices utilized heretofore have worked with some degree of success, they have had shortcomings which have detracted from their usefulness. More specifically, the methodology as discussed above has not produced reliable results when the sodium iodide spectra is collected from measurements of relatively small quantities of material at increasing stand-off distances. Further, it should be understood that some gamma-ray spectra contain ill-defined peaks for certain chemical elements of interest. A primary example of this are the typical weak, high energy peaks such as those used for the detection of nitrogen in spectra obtained from sodium iodide detectors and which would indicate the presence of an explosive. With regard to these energy peaks, they typically are broad and often overlap. The poor peak resolution combined with the low number of counts available when attempting to identify small elemental quantities producing these weak peaks make it difficult to determine accurate peak widths, and peak region boundaries in any spectra. These same conditions also make energy calibrations less precise so that there may be considerable uncertainty in properly centering regions of interest based upon an energy range surrounding energies for known gamma-rays. Under these conditions, identifying the optimal region boundaries for summing, Gaussian peak fitting or other methods of elemental detection becomes quite difficult. Those skilled in the art understand that if the region boundaries are not often optimally defined, the detection capabilities for small amounts of materials will be significantly degraded.
Therefore, a method for detecting an element which avoids the shortcomings attendant with the prior art methodology and devices utilized heretofore is the subject matter of the present application.